All of the U.S. patents cited throughout this specification are hereby entirely incorporated herein.
Ultraviolet absorber compounds have been utilized for a number of protective applications, including within compositions for covering skin, on and within apparel and other types of textiles, within transparent plastic containers, and the like, to combat the harmful and degradable effects of certain wavelengths of light in the UV spectrum. The best known UV absorbers are benzotriazoles, available from Ciba-Geigy under the tradename Tinuvin.RTM., and benzophenones, available from Cytec Industries under the trademark Cyasorb.TM.. Such compounds are highly effective in their UV absorber capacity; however, they are quite costly, can prove difficult to incorporate within different target media, and tend to migrate from within certain types of media (such as plastics). Furthermore, these two well known types of UV absorbers present handling difficulties in that they are generally produced and utilized in powder form and have relatively low melting points. Particularly, within plastic media, the powder form of these compounds is problematic; a liquid is much easier to handle, does not require melting, and provides more effective and thorough mixing throughout the target plastic. Additionally, these previously utilized UV absorbers provide UV protection over a relatively narrow range of wavelengths (.lambda..sub.max from about 290 to about 340 nm for benzotriazoles; from 260 to 300 run for benzophenones), which ultimately leaves a potentially damaging range of unprotected UV exposure (to about 400 nm). Thus, there exists a need to provide a highly effective, liquid ultraviolet absorber which exhibits a versatility to be incorporated within or applied to different and various media and substrates and which, alternatively, can provide protection over the range of wavelengths in the UV spectrum of from about 290 to about 400 nm (in order to provide the best overall protection from possible harm and/or degradation associated with UV exposure).
Methine-based compounds, in particular certain malonate derivatives, as in European Patent Abstract 350-386-A, to L'Oreal SA, are useful as UV absorbers in cosmetic sunscreen compositions, are generally inexpensive to make, and provide UV protection in the spectrum from about 280 to about 360 nm. However, such compounds are highly soluble in organic solvents and would therefore easily migrate from solid compositions, such as plastics, upon introduction therein. Thus, although the utilization of an effective UV absorber, such as a malonate derivative, within plastics, may be highly desirable, such has never been taught nor fairly suggested within the prior UV absorber art due to the great difficulty in producing such a stable, and thus highly effective, UV absorbing composition from such a methine-based source. There exists a need then to produce an inexpensive UV absorber, preferably methine-based, which possesses the requisite ability to remain within media such as thermoplastics and the like (as noted above), and thus provide necessary and desirable protection from degradation due to UV exposure.
It has now been found that through the addition of polyoxyalkylene chains onto a methine-based ultraviolet absorber compound, greater versatility of potential uses for the new UV absorber is provided. Therefore, it has been found that such polyoxyalkylenated methine-based compounds provide a UV absorber which is highly effective in filtering harmful UV-A and UV-B rays over a broad spectrum (.lambda..sub.max from about 320 to about 400 nm, more preferably from about 350 to 390 nm). Furthermore, it has been found that in combination with a benzotriazole and/or a hydroxybenzophenone, or other similar type of UV absorber compound, the resultant composition is accorded protection from a great amount of potentially damaging UV radiation (from approximately 250 to about 400 nm). Additionally, such a combination is highly stable within the target media, and thus provides long-term protection to the desired sample stored within the treated plastic article.
Although some interest has been demonstrated within the area of methine-based UV absorber compounds (i.e., L'Oreal's malonate derivatives), to date there has been no disclosure or fair suggestion regarding the utilization of the polyoxyalkylenated derivatives of such UV absorbers in that capacity within certain media (such as, for example, plastics), or on other surfaces (skin, textiles, for example), or in other applications (inks, and the like, for example). In particular, no disclosures exist concerning methine-based polyalkylenated UV absorber compound which provide an effective protected range of wavelengths from UV exposure of from about 320 to about 400 nm. There is thus a great need within the Uv absorber market, and most particularly within the transparent plastic film and container markets (for storing and protecting food, pills, and the like) for such types of improvements associated with relatively inexpensive materials and processes provided by the inventive polyoxyalkylenated methine-based UV absorber compounds.